A transmission control protocol (TCP) is generally applied to the packet switched (PS) services in a wireless field. A wireless network is characterized by features such as high delay, variable data rate, asymmetry, delay peak, and bandwidth jitter, which may affect the performance of TCP. With the development of data services, quality of service (QoS) required by a user is becoming higher and higher. Therefore, a need arises to enhance the transmission performance of TCP in a radio bearer.
When data transmission occurs in the uplink and downlink directions simultaneously, the transmission process includes an upload process and a download process. In the upload process, a terminal sends a data packet to a server. After receiving an acknowledge (ACK) packet from the server, the terminal slides the window to send a new data packet. In the download process, the server sends a data packet to the terminal. after receiving an ACK packet from the terminal, the server slides the window to send a new data packet. When the server sends a data packet, the server also sends an ACK packet corresponding to the uplink data packet. When the terminal sends a data packet, the terminal also sends an ACK packet corresponding to the downlink data packet.
The throughput performance demonstrated when data is transmitted in both uplink and downlink simultaneously is an important performance indicator for evaluating a wireless system. However, in the existing network, the data rate in the downlink direction is low and unstable when data is transmitted in both uplink and downlink directions simultaneously, because the ACK corresponding to the downlink data packet is generally arranged after the uplink data packet at the TCP layer of the terminal, which leads to the delay of the ACK corresponding to the downlink data packet. Therefore the performance of the downlink data transmission is negatively affected and user experience is poor.